1. Field of the Invention
The invention relates to a ventilation device for a fuel tank having an equalizing opening arrangable in a fuel tank for equalizing a pressure in the fuel tank with an ambient pressure surrounding the fuel tank and having an antisurge element arranged in front of the equalizing opening.
2. Description of the Related Art
Ventilation devices for equalizing the pressure in a fuel tank with ambient pressure connect that region of the fuel tank which is not filled with fuel to the ambient surroundings via an activated carbon filter and are known in practice. The ventilation device allows air to flow from the surroundings into the fuel tank as the fuel is consumed and for gases to escape from the fuel tank when there is thermal expansion of the fuel or when the tank is filled via a filler neck. Ventilation devices which are known in practice have a float valve or a return surge flap as the antisurge element. When the fuel is sloshing around within the fuel tank, this antisurge element prevents fuel from penetrating through the ventilation opening into the ventilation line. The antisurge element prevents fuel from penetrating into the activated carbon filter and therefore from damaging it.
A problem of the known antisurge elements is that they have movable components and are therefore very susceptible to failure. Furthermore, the known antisurge elements require very cost-intensive mounting or guidance for the movable component and sealing surfaces of complicated design.
It is an object of the present invention to provide a ventilation device for equalizing the pressure in a fuel tank with the ambient pressure surrounding the fuel tank such that the ventilation device has a structure which is particularly unsusceptible to failure and may be manufactured cost-effectively.
The object of the present invention is achieved by a ventilation device for a fuel tank having an equalizing opening for equalizing the pressure in the fuel tank with the surrounding ambient air and an antisurge element designed as a fixed component with a plurality of channels. Each of the plural channels of the antisurge element has a small diameter in comparison to the equalizing opening.
The pressure in the fuel tank is equalized with the surroundings via the channels. Because of their small diameter, the channels offer a substantially smaller resistance to a gas flow than to a liquid flow. The larger resistance to liquid flow prevents fuel that is sloshing around in the fuel tank from penetrating into the ventilation line. However, the channels nevertheless provide sufficient equalization of the pressure. Since the ventilation device does not require any movable components in the region of the antisurge element, it has a structure which is particularly unsusceptible to failure and may be manufactured cost-effectively.
The antisurge element may, for example, have a plurality of lattices which are arranged one behind another and have a designated mesh width. However, according to an advantageous development of the invention, fuel which is sloshing around against the antisurge element is reliably held back if the antisurge element is designed as a porous sintered part.
According to another embodiment of the present invention, the antisurge element is particularly cost-effective if it is manufactured from plastic. A sintering process for plastic is known, for example, from the manufacture of floats for fuel tanks. The sintering process includes producing granules made entirely of plastic by extrusion and pressing the plastic granules while they are hot. The diameters of channels produced between the granule grains may be set by adjusting the grain size of the plastic granules, the temperature of the granules during the step of pressing and the amount of pressure used during the sintering process.
According to another embodiment of the present invention, the installation of the antisurge element proves to be particularly simple if the antisurge element is welded, clipped or pressed to the component having the equalizing opening.
The equalizing openings are frequently formed by open ends of ventilation lines. According to another embodiment of the present invention, the fastening of the antisurge element in front of the equalizing opening proves to be particularly simple if the antisurge element partially surrounds a ventilation line in which the equalizing opening is arranged in the region of the equalizing opening.
According to yet another embodiment of the present invention, the antisurge element are connectable to ventilation lines of virtually any design when the antisurge element is made of a disk-shaped design and is inserted in a connecting nipple designed for connection to a ventilation line. In ventilation lines guided outside the fuel tank, the connecting nipple may simply be inserted into the wall of the fuel tank.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.